EE WAS PREPARING TO REPAIR A BROKEN COUPLING ON THE WASTE DUST MIXER AND WAS USING A HAND HELD SHOVEL TO SCOOP GREASE & DIRT FROM UNDER THE GEARBOX PRIOR TO WORK ON THE COUPLING. WHEN HE BENT DOWN TO LIFT UP A SHOVEL FULL OF GREASE/DIRT, HE FELT A POP IN HIS LOWER BACK. EE SOUGHT CHIROPRACTIC TREATMENT ON SEVERAL OCCASIONS & WAS PLACED ON LIGHT DUTY ON 10/13/03.